A longstanding theory in evolutionary biology is that venomous predators like rattlesnakes often develop complex venoms in order to immobilize the widest variety of prey. Ultimately, Margres and colleagues collected venom from 83 rattlesnakes, some as large as four-feet long. Like many evolutionary biologists, Margres and Hirst assumed the larger islands’ biodiversity would result in more complex rattlesnake venoms designed for a wider range of prey. Subsequent analysis of the venom trove revealed that the islands with more competition and space were home to more specialized rattlesnake toxins. They also intend to test how well existing antivenoms work on the rattlesnake venom collected from the Gulf of California vipers.